FAILURE DIAGNOSIS DEVICE AND POWER CONVERSION DEVICE

To realize a failure diagnosis device that has a small size and is in a low cost, capable of easily performing diagnosis of a failure of a power semiconductor element for a short time in a power conversion device having a pair of the power semiconductor element connected in parallel, and realize the power conversion device.SOLUTION: A failure diagnosis device 1 that performs diagnosis of a failure of a power semiconductor element in a power conversion device 100 having a pair of the power semiconductor elements connected in parallel, comprises: a gate driving part 11 that alternately supplies a positive voltage and a negative voltage, or a zero voltage to between a control terminal of the power semiconductor elements and a current flow terminal; a detection part 12 that detects a voltage or a current output by the power conversion device 100; and a diagnosis part 13 that performs the present/absence of the failure of the pair of the power semiconductor elements on the basis of a voltage value or a current value detected by the detection part 12. The positive voltage for the diagnosis supplied from the gate driving part 11 at the time of the diagnosis by the diagnosis part 13 is smaller than the positive voltage for driving to be supplied from the gate driving part 11 at the time of a power conversion operation by the power conversion device 100.SELECTED DRAWING: Figure 1 【課題】複数個並列に接続された電力用半導体素子の組を有する電力変換装置において、電力用半導体素子の故障を短時間で容易に診断できる小型で低コストの故障診断装置及びこれを備える電力変換装置を実現する。【解決手段】複数個並列に接続された電力用半導体素子の組を有する電力変換装置１００における電力用半導体素子の故障を診断する故障診断装置１は、電力用半導体素子の制御端子と電流流出端子との間に、正電圧と負電圧またはゼロ電圧とを交互に供給するゲート駆動部１１と、電力変換装置１００が出力する電圧または電流を検出する検出部１２と、検出部１２が検出した電圧または電流の値に基づき、電力用半導体素子の組の故障の有無を診断する診断部１３と、を備え、診断部１３による診断時にゲート駆動部１１から供給される診断用の正電圧は、電力変換装置１００による電力変換動作時にゲート駆動部１１から供給される駆動用の正電圧よりも小さい。【選択図】図１